JPH07316632A - Structure of vessel bottom of lower vessel in rh vacuum degassing equipment - Google Patents

Abstract

PURPOSE:To prevent the damage to a lined refractory accompanied with the expansion and the shrinkage of an outer iron shell by forming the outer iron shell at the bottom part of a lower vessel drum to a downward curving through-shape structure between circulating flow tubes. CONSTITUTION:Two circulating flow tubes 4 are formed at the bottom part of the lower vessel drum arranged with the lined refractory 6 in the cylindrical outer iron shell 2 and immersion tubes 8 are fitted to the tip parts thereof through flange parts 7. In this drum, the outer iron shell 3 at the bottom part of the vessel is formed to the downward curving through-shape structure in the direction connecting the centers of both circulating flow tubes 4. At this time, inclining parts are arranged at the outer iron shell 5 of the circulating flow tube parts projected to the lower part at the vessel bottom part of the drum, and further, the inclining part is desirable to be formed in a truncated elliptic conical shape tapered downward so that the outer peripheral side has a sharper inclination than the center side. By this constitution, it is prevented that the outer iron shell part of the circulating flow tube part is opened to a reverse V shape caused by the expansion and shrinkage at the time of dipping or pulling out the immersion tubes 8 to and from molten steel and that the lined refractory 6 is cracked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of the outer shell iron shell of the tank bottom of the lower tank of the RH vacuum degassing facility and the outer shell iron shell of the reflux pipe section.

[0002]

2. Description of the Related Art A vacuum tank of an RH type vacuum degassing facility is formed in a cylindrical shape and can be divided into an upper tank and a lower tank, or an upper tank, an intermediate tank and a lower tank by a flange. . Exhaust gas pipes, alloy injection pipes, etc. are provided above the upper tank, and reflux pipes and dip pipes are arranged at the lower end of the lower tank.Refractory materials in each part are arranged according to their respective amounts of wear. The so-called "zoned lining", in which the proper material is selected and lining is applied, and the sidewall is also selected and lining according to the amount of wear, and the lining thickness of the lining brick is adjusted Many stacking methods have been devised and adopted in order to balance the damage in each part of the furnace, such as In terms of material, it is known in recent years that mag-black bricks are the main components.

In this vacuum tank, as is well known, the dip tube arranged below the lower tank is dipped in the molten steel in the ladle to evacuate the tank, and one dip tube (rise pipe) is used to discharge argon. By injecting an inert gas such as, the molten steel flows into the tank and is scattered to degas, and the degassed molten steel is discharged from the other dipping pipe (downcomer pipe) and returns to the ladle. This is a degassing facility for degassing by continuing this.

[0004]

At the same time, the above R
In the lower tank of the H type vacuum degassing equipment, when the dip tube is immersed in the molten steel in the ladle for vacuum degassing treatment, the high temperature of the molten steel and the wear caused by the shocking turbulence due to the recirculation, or Wear of the refractory lining occurs due to spalling caused by rapid heating and cooling due to repeated use.

In particular, when the outer shell of the lower tank is formed on a flat surface and the dip tube is immersed in the molten steel in the ladle for vacuum degassing, it is heated by radiant heat from the molten steel. The central part expands most, and when the ladle is removed, it is cooled by the outside air and contracts. This expansion / contraction causes displacement of two recirculation pipe outer shells, which vertically project downward from the outer shell of the bottom of the lower tank, in the direction of "C".
Correspondingly, the refractory lining constructed inside the outer shell will also move in tandem, causing joints to become loose, joints to be broken, and cracks to occur, making the aforementioned problems even more pronounced. Will appear in.

The expansion and contraction of the iron shell of the outer shell of the bottom of the tank is larger than that of the outer shell which shrinks during repeated use due to the change from elastic deformation to plastic deformation, and the central portion of the bottom of the tank gradually hangs down. The outer shells of the two recirculation pipes that project into the open also open in a C shape, and when the immersion pipe is immersed in the molten steel in the ladle for vacuum degassing, the degree of deformation is As it becomes larger, it will remain open in a V shape, which not only complicates the construction of the refractory lining on the bottom of the tank, but also the refractory lining the reflux pipe during use. A step may be formed between the lower surface and the lower surface of the flange that connects the immersion pipe.

[0007] In view of this, the present invention takes the shape of the letter "C" by interlocking the outer shell of the recirculation pipe even if the outer shell of the bottom of the tank is expanded and contracted by being heated and cooled. The purpose of the present invention is to provide a structure of the bottom of the tank that is difficult to displace in the opening and closing directions.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention relates to a can body for a lower tank of an RH vacuum degassing equipment. The skin structure is formed in a downwardly curved gutter shape in a direction connecting the centers of the two reflux pipes, and is in the tank bottom structure of the lower tank can body of the RH degassing equipment, and the tank bottom part Is provided on the outer shell of the recirculation pipe portion projecting downward from the bottom of the degassing tank, and the slanted portion is formed in a truncated conical shape tapered downward toward the outer side rather than the center side of the degassing tank. It is characterized by forming.

[0009]

In the present invention, the outer shell structure of the bottom of the lower can body is flat in the direction connecting the centers of the two reflux tubes (hereinafter referred to as "recirculation direction"), and the direction perpendicular thereto (hereinafter "anti-recirculation"). Direction) is formed in the shape of a gutter curved downward, and an inclined portion is provided on the outer shell iron shell of the reflux pipe portion projecting below the bottom portion of the tank, and the inclined portion is formed in the degassing tank. Since the outer peripheral side is formed to be steeper than the center side, even if it is heated and cooled by receiving radiant heat from molten steel, the expansion and contraction of the outer shell of the tank bottom in the recirculation direction is linear (in a curved shape). As a result, it is possible to prevent the reflux pipe from displacing in a “C” shape, which can prevent the joint refractory from being broken or cracked. The life of the pipe part can be greatly extended.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to an embodiment shown in the drawings.

FIG. 1 shows a longitudinal section of a lower tank according to the present invention, and FIG. 2 shows a longitudinal section corresponding to the line AA of FIG.
The basic structure is similar to the conventional one, in which the outer shell 2 having the flange 1 at the upper end is formed in a cylindrical shape on the side surface, and the outer shell 3 at the bottom of the tank is vertically projected downwardly from the two pieces. The outer shell 5 of the recirculation pipe 4 is provided, and the refractory 6 is lined inside with a proper lining. The dip pipe 8 is detachably connected to the lower part of the refractory 6 through the flange 7. It has a different configuration.

At the bottom of the tank, the outer shell 3 of the bottom of the tank is formed in a gutter-like shape in the recirculation direction (the direction on the line connecting the two recirculation pipes) (see FIG. 1), and the anti-recirculation direction (recirculation direction). "R" is added in the direction of forming a right angle) to form a trough shape curved downward (see FIGS. 2 and 3). The iron skin 5 is in the shape of a truncated cone that tapers downward, its junction with the bottom of the tank and its cross section are oval, and a dip tube 8 is attached below it through a flange 7. .

When the dip pipe 8 is immersed in molten steel to perform degassing, the outer shell 3 at the bottom of the tank is curved downward at the center in the recirculation direction due to the high-temperature radiant heat of the molten steel. It is formed in a gutter shape in order to prevent the phenomenon of being deformed into the shape of a gutter. The tank bottom outer shell 3 formed in an oval shape is curved in the major axis direction to form a gutter shape, and formed in a cylindrical shape on it. The outer shell iron skin 2 on the side surface is placed and rounded around the outer shell, and they are connected by means such as welding. Further, two recirculation pipe outer shells 5 which are formed in a predetermined position at a lower portion thereof and are formed in a downwardly tapered truncated cone shape are provided.

The outer shell 3 at the bottom of the tank has a stronger strength against the load of the refractory lining 6 and the dipping pipe 8 as the "R" added in the anti-recirculation direction is set smaller, and the recirculation direction is curved. Although it is possible to prevent it from forming into a shape, the lining refractory 6 at the bottom of the tank is usually laid flat on the bottom with castable refractory or other irregularly shaped refractory to give a level, and the refractory lining is placed on top of it. If the "R" is set too small, the height dimension formed by the arc and the chord becomes large, and a castable refractory or other irregular refractory is laid thick to absorb the curved surface, or The lower surface side of the lined refractory brick will be cut along the curved surface and absorbed. Therefore, the height dimension formed by the arc and the chord is 50 to 200 m.
It is provided by setting the "R" dimension based on the diameter dimension of the side surface outer shell iron shell 2 while keeping it to about m.

Two recirculation pipe outer shells 5 provided downward of the tank bottom outer shell 3 suspend a dipping pipe 8 which is detachably connected via a flange 7. And the tension for suspending the dip pipe 8 which is a heavy object is made as small as possible, and the load by the refractory lining 6 and the dip pipe 8 and the expansion / contraction by heating / cooling,
The steel-made tank bottom outer shell 3 becomes plastically deformed when the stress exceeds the limit proportional to the stress and strain at an early stage (exceeds the above limit), and on the other hand, thermal strain due to heating. In order to suppress these, an inclined portion is provided, and when formed vertically, the bending stress applied to the tank bottom outer shell 3 becomes large, and the outer shell iron shell at the center of the tank bottom is increased. 3 is deformed, so that the reflux direction is easily deformed into a curved shape. Therefore, by decomposing the bending stress, the bending stress on the center side is made smaller than the outer circumference side in the recirculation direction, and in order to suppress the bending stress of the tank bottom shell shell 3, the outer circumference side is steeply inclined from the center side. The inclination angle formed by the vertical line is set to, for example, about 0 to 30 ° on the outer peripheral side and about 25 to 60 ° on the central side.

Therefore, since the outer shell iron shell 3 at the bottom of the tank is curved in the anti-recirculation direction and provided in a gutter shape with the above-described structure, when the central portion of the outer shell iron shell 3 at the bottom of the tank expands, it bends in the direction of reflux. It can be prevented from hanging down like a line, and the phenomenon that the outer shell iron shell 5 is deformed and opened / closed in a "H" shape in conjunction with the expansion and contraction of the portion can be suppressed. It is possible to prevent occurrence of joint breakage, cracks, etc. of the object 6, and it is possible to significantly extend the service life.

Furthermore, if the tank bottom outer shell iron shell 3 is formed so as to be slightly curved in the direction of recirculation, the lining refractory material 6 and the dip tube 8 will have a heavy load. It is possible to increase the bending strength, and further prevent damage to the refractory lining 6 due to the deformation of the can body, and to further extend the useful life.

[0018]

As described above, according to the present invention, R
H vacuum degassing equipment In the can for the lower tank, the tank bottom structure of the can is formed in a downwardly curved curved trough shape, so that the dipping pipe is immersed in molten steel for degassing treatment. When it was carried out, the phenomenon that the central part in the circulating direction was deformed into a downward curved shape due to the high temperature radiant heat of the molten steel was suppressed, and the outer shell shell of the reflux pipe projecting downward was interlocked. It can be prevented from being deformed and opened / closed in the shape of “C”. In addition, by providing an inclined portion on the outer shell of the recirculation pipe portion, and forming the inclined portion so that the outer peripheral side is steeper than the central side and is formed in the shape of a truncated conical body tapered downward, It is possible to reduce the bending stress of the outer shell of the tank bottom by the dip pipe which is, and to prevent the circulation direction of the outer shell of the bottom of the tank from extending and hanging downward in a curved shape. It is possible to prevent breakage of joints, cracks, and the like caused by the deformation stress of the iron skin, and to significantly extend the life of the reflux pipe section.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a lower tank showing an example of the present invention.

FIG. 2 is a vertical sectional view taken along the line AA of FIG.

FIG. 3 is a perspective view of the lower tank according to the present invention as seen obliquely from below.

[Explanation of symbols] 1 Flange 2 Cylindrical outer shell iron shell 3 Tank bottom outer shell iron shell 4 Recirculation pipe 5 Recirculation pipe outer shell iron skin 6 Inner refractory 7 Flange 8 Immersion pipe

Claims (2)

[Claims] 1. A can body for a lower tank of an RH vacuum degassing facility, wherein the outer shell skin structure at the bottom of the can body tank has a downwardly curved gutter shape in a direction connecting the centers of two reflux tubes. The bottom structure of the lower tank can body of the RH degassing facility characterized by being formed. 2. A can body for a lower tank of a RH vacuum degassing equipment, wherein an inclined portion is provided on an outer shell iron shell of a reflux pipe portion projecting below the bottom portion of the can body tank, and the inclined portion is provided in the degassing tank. A bottom structure of a lower tank can body of an RH degassing facility, characterized in that the RH degassing equipment is formed in a frusto-conical shape in which the outer peripheral side is steeper than the central side and is tapered downward.